/*
 * Copyright (c) 1996, 2000, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package java.lang;

/**
 * Signals that an unexpected exception has occurred in a static initializer.
 * An <code>ExceptionInInitializerError</code> is thrown to indicate that an
 * exception occurred during evaluation of a static initializer or the
 * initializer for a static variable.
 *
 * <p>As of release 1.4, this exception has been retrofitted to conform to
 * the general purpose exception-chaining mechanism.  The "saved throwable
 * object" that may be provided at construction time and accessed via
 * the {@link #getException()} method is now known as the <i>cause</i>,
 * and may be accessed via the {@link Throwable#getCause()} method, as well
 * as the aforementioned "legacy method."
 *
 * @author Frank Yellin
 * @since JDK1.1
 */
public class ExceptionInInitializerError extends LinkageError {

  /**
   * Use serialVersionUID from JDK 1.1.X for interoperability
   */
  private static final long serialVersionUID = 1521711792217232256L;

  /**
   * This field holds the exception if the
   * ExceptionInInitializerError(Throwable thrown) constructor was
   * used to instantiate the object
   *
   * @serial
   */
  private Throwable exception;

  /**
   * Constructs an <code>ExceptionInInitializerError</code> with
   * <code>null</code> as its detail message string and with no saved
   * throwable object.
   * A detail message is a String that describes this particular exception.
   */
  public ExceptionInInitializerError() {
    initCause(null);  // Disallow subsequent initCause
  }

  /**
   * Constructs a new <code>ExceptionInInitializerError</code> class by
   * saving a reference to the <code>Throwable</code> object thrown for
   * later retrieval by the {@link #getException()} method. The detail
   * message string is set to <code>null</code>.
   *
   * @param thrown The exception thrown
   */
  public ExceptionInInitializerError(Throwable thrown) {
    initCause(null);  // Disallow subsequent initCause
    this.exception = thrown;
  }

  /**
   * Constructs an ExceptionInInitializerError with the specified detail
   * message string.  A detail message is a String that describes this
   * particular exception. The detail message string is saved for later
   * retrieval by the {@link Throwable#getMessage()} method. There is no
   * saved throwable object.
   *
   * @param s the detail message
   */
  public ExceptionInInitializerError(String s) {
    super(s);
    initCause(null);  // Disallow subsequent initCause
  }

  /**
   * Returns the exception that occurred during a static initialization that
   * caused this error to be created.
   *
   * <p>This method predates the general-purpose exception chaining facility.
   * The {@link Throwable#getCause()} method is now the preferred means of
   * obtaining this information.
   *
   * @return the saved throwable object of this <code>ExceptionInInitializerError</code>, or
   * <code>null</code> if this <code>ExceptionInInitializerError</code> has no saved throwable
   * object.
   */
  public Throwable getException() {
    return exception;
  }

  /**
   * Returns the cause of this error (the exception that occurred
   * during a static initialization that caused this error to be created).
   *
   * @return the cause of this error or <code>null</code> if the cause is nonexistent or unknown.
   * @since 1.4
   */
  public Throwable getCause() {
    return exception;
  }
}
